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Showing papers on "Linear particle accelerator published in 1976"


Journal ArticleDOI
TL;DR: The history of experiments bearing on the origin of optical activity in nature by parity non-conservation during the β-decay of radioactive isotopes is briefly reviewed in this article.
Abstract: The history of experiments bearing on the origin of optical activity in nature by parity non-conservation during the β-decay of radioactive isotopes is briefly reviewed. Following this, we present a more detailed description of our recent published and unpublished data and calculations regarding the generation of optical activity in DL-leucine by means of artificially produced longitudinally polarized electrons from a linear accelerator.

35 citations


Journal ArticleDOI
TL;DR: An alternative scattering and collimation system for the Siemens Mevatron XII linear accelerator, designed to minimize electron scatter and improve the safety of patient setup, is developed, with no mechanical connection between the machine and the final collimator.
Abstract: The original scattering and collimation system for the Siemens Mevatron XII linear accelerator used a lead scattering foil and box‐type plastic collimators. This arrangement achieves excellent field flatness by repeated electron scattering. The electrons reaching the patient are widely distributed in energy and direction. This has detrimental effects on the depth‐dose curves: slower falloff and increased surface dose. We have developed an alternative system for this accelerator, designed to minimize electron scatter and improve the safety of patient setup. Primary‐electron scatter occurs in the bending‐magnet exit window. Field uniformity is accomplished with a flattener of thin aluminum discs of different diameters, piled concentrically. An adjustable electron collimator 25 cm from the patient limits beam size, and a final electron collimator, either a cutout from lead sheet or a a custom‐made collimator of Lipowitz’s metal, in contact with the patient, define the area to be treated. This design results in lower surface dose, sharper dose falloff, bremsstrahlung contamination ⩽1%, and a field flatness expressed by a homogeneity index >0.8 for large fields. Since there is no mechanical connection between the machine and the final collimator, the safety aspects of the system are considerably improved.

33 citations


Journal ArticleDOI
TL;DR: The bremsstrahlung spectrum from an 8-MeV linear accelerator has been measured using a NaI(T1) spectrometer system and shows a low-energy cutoff at 0.4 MeV and the maximum photon energy to be approximately 6% greater than the nominal energy.
Abstract: The bremsstrahlung spectrum from an 8‐MeV linear accelerator has been measured using a NaI(T1) spectrometer system. The spectrum shows a low‐energy cutoff at 0.4 MeV and the maximum photon energy to be approximately 6% greater than the nominal energy. The maximum emission of energy fluence was 1.6 and 1.8 MeV for measured and calculated values, respectively. The fast neutron dose in the photon beam was approximately 0.09% of the x‐ray dose. The weighted mean energy was 2.3 MeV, measured value, and 2.4 MeV, calculated value.

33 citations


Patent
22 Dec 1976
TL;DR: In this paper, an attenuator and a phase shifter between the two sections allow adjustment in the energy added to the particles in the downstream standing-wave section without disturbing the synchronism of the beam with the upstream accelerating section.
Abstract: An accelerator for a linear beam of charged particles has a first accelerating section upstream which modulates and accelerates the dc beam. This section is a traveling-wave circuit through which the entire rf power flows from the driving source. Output power from the other end of the traveling-wave section flows through a transmission line to a standing wave accelerating section downstream of the input section. An attenuator and a phase shifter between the two sections allow adjustment in the energy added to the particles in the downstream standing-wave section without disturbing the synchronism of the beam with the upstream accelerating section. As a result a high efficiency of acceleration and narrow energy spread of the final accelerated beam are achieved over a wide range of particle energies.

25 citations


Patent
16 Nov 1976
TL;DR: In this article, a standing wave type microwave linear particle accelerator excited by a magnetron and producing bursts of high energy electrons which can selectively bombard either a neutron emitting target or a photon emitting target is described.
Abstract: In accordance with an illustrative embodiment of the present invention, a logging sonde includes a standing wave type microwave linear particle accelerator excited by a magnetron and producing bursts of high energy electrons which can selectively bombard either a neutron emitting target or a photon emitting target. Means are provided to sense the variations in the amplitude of the microwave field in the linear accelerator and to control the frequency of the magnetron so as to maintain the amplitude of the accelerating field at a reference value representative of the expected maximum amplitude value at resonance. Means are also provided to sense the variations in the temperature of the linear accelerator and to control the frequency of the magnetron so as to compensate for the variations in the resonant frequency of the accelerator that result from temperature induced changes the length thereof.

24 citations


Journal ArticleDOI
TL;DR: Using 13.5-GeV beams at Stanford Linear Accelerator Center, electron and positron inelastic scattering have been compared over the range 1.2 and 1.5 as mentioned in this paper.
Abstract: Using 13.5--GeV beams at Stanford Linear Accelerator Center, electron and positron inelastic scattering have been compared over the range 1.2

21 citations


Journal ArticleDOI
TL;DR: In this paper, a coherent transferral of the density information from the protons in the bunch to secondary emission electrons released from a foil in the beam's path is presented for measuring the longitudinal bunch density distribution in a proton linac which performs this measurement in a nondestructive manner and allows direct presentation on a slow X-Y display.

18 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured the width of the Cerenkov light pulse generated by the electron beam using a streak camera-TV camera-computer system, and showed that a broad energy spectrum for the electrons or improper focusing into a 270° bending magnet increased the pulse width after it had traversed the magnet.
Abstract: We describe the technique and the results of a measurement of the width of a fine structure pulse from our L‐band electron linear accelerator. The pulse width was measured by measuring the width of the Cerenkov light pulse generated by the electron beam using a streak camera–TV camera–computer system. With very low beam currents, a pulse width of 20 psec (FWHM) was measured, while at higher beam currents a pulse width of 27 psec was measured showing a space‐charge effect. In addition, a broad energy spectrum for the electrons or improper focusing into a 270° bending magnet was also shown to increase the pulse width of the beam after it had traversed the magnet.

12 citations


Journal ArticleDOI
TL;DR: A system has been developed for the utilization of a Wang 600-14 programmable calculator to acquire, verify and record treatment parameters from a linear accelerator.
Abstract: A system has been developed for the utilization of a Wang 600-14 programmable calculator to acquire, verify and record treatment parameters from a linear accelerator. The hardware and software components and operation of the system are briefly described. The system is in use daily.

12 citations


Journal ArticleDOI
Peter J. Gollon1
TL;DR: In this article, a general introduction is given for those not actively involved in this area, and a general overview of the issues involved in the design of a new accelerator is discussed.
Abstract: At all accelerators with energies greater than some tens of MeV, induced radioactivity results whenever beams interact with accelerator or beam transport components. Typically these interactions occur at injection and extraction points and beam splitting stations. Losses at these points are not desirable, and great efforts are often required to reduce them. Beam losses also occur at collimators, scrapers, target areas and beam dumps; these losses are deliberate and cannot be reduced. Consequently, these are usually the most radioactive areas of the accelerator, and work near them is the largest source of radiation exposure at all laboratories. It is therefore necessary to be able to anticipate the magnitude of the problems involved in such work, in order to minimize those problems in the design of a new facility. While these loss points are common to all accelerators, the magnitude of the resulting problems depends on many factors unique to each accelerator: the type of particle accelerated, the particle energy, and the geometry and composition of the items being struck. These considerations are discussed, and a general introduction is given for those not actively involved in this area.

12 citations


Patent
27 Dec 1976
TL;DR: In this article, a standing-wave linear charged particle accelerator is described, which comprises a plurality of interlaced substructures, with each substructure having accelerating cavities along the particle beam path and having side cavities disposed away from the beam path for electromagnetically coupling the accelerating cavity.
Abstract: A standing-wave linear charged particle accelerator is disclosed which comprises a plurality of interlaced substructures, with each substructure having a plurality of accelerating cavities disposed along the particle beam path and having side cavities disposed away from the beam path for electromagnetically coupling the accelerating cavities. A standing radio-frequency electromagnetic wave is supported in each substructure, with the wave in each substructure being phased with respect to the wave in every other substructure so that the particle beam will experience a maximum energy gain throughout its path through the accelerator. A single input waveguide is divided into plural branches to individually drive each of the substructures.

Journal ArticleDOI
TL;DR: The dosimetic properties of interest in a megavoltage therapy X-ray beam are per cent depth dose, skin sparing, penumbra, radiation field flatness and symmetry, which are parametrized as function of field size and depth.
Abstract: The dosimetic properties of interest in a megavoltage therapy X-ray beam are per cent depth dose, skin sparing, penumbra, radiation field flatness and symmetry. The 10 MV X-ray beam from the Varian Associates Clinac 18 Linear Accelerator is studied with regard to these points. The primary points of interest are a 50% depth dose for a 10 × 10 cm 2 field at 18.0 cm in water and a depth of maximum dose of 2.4 ± 0.1 cm in water. Transmission measurements in aluminum and lead yielded 50% transmission thicknesses of 73.2 and 13.4 mm respectively. The flatness of the fields are parametrized as function of field size and depth. Decrement line plots are graphed and isodose curves for selected field sizes are presented.

Patent
03 Dec 1976
TL;DR: In this paper, a controlled-frequency arrangement for feeding a linear charged particle accelerator and enabling the power reflected by the accelerator toward the microwave generator feeding it to be minimized when the accelerator is loaded by the particle beam is presented.
Abstract: A controlled-frequency arrangement for feeding a linear charged particle accelerator and enabling the power reflected by the accelerator toward the microwave generator feeding it to be minimized when the accelerator is loaded by the particle beam. The feeding arrangement comprises means for obtaining a continuous signal v of which the amplitude is proportional to the phase shift Δφ which may exist between the microwave signal injected into the accelerator and the signal stored in the accelerator, and for comparing this signal v with a variable reference signal v 4 to obtain an error signal v - v r which, when applied to a frequency controlling system, causes the frequency F of the microwave generator associated with the accelerator to be suitably varied, this variation in frequency αF enabling the phase shift αφ to be eliminated.

Journal ArticleDOI
W. Ash1
TL;DR: A simple, inexpensive device for quickly making large quantities of small, uniform, frozen beads of alcohol for polarized targets is described in this article, which has been successfully used at Stanford Linear Accelerator Center for about two years.

Book
01 Jan 1976
Abstract: The experiments described in this thesis were initially prompted by interest .. , the radiation loss of relativistic electron rings passing through periodic structures. Later the same experiments became relevant to the theory of energy loss of electrons in large storage rings. In both of these cases energy loss to the higher order modes of the respective structures could seriously limit their effective operation. In these experiments, single bunches of electrons with intensities up to 7 x 10S electrons per bunch are accelerated through the SLAC three-kilometer accelerator, and their energy spectra are analyzed. Early experiments over a wide energy range (900 MeV to 19 GeV) demonstrated that the energy loss was proportional to the total charge m the bunch but was im$,ependent of beam energy. The average energy loss of a single bunch normalized to 10 electrons was initially measured to be 38 MeV. While this work was starting, E. Keil at CERN, Geneva, Switzerland, was developing a theory and a computer program based on cavity modal analysis to identify the higher-order modes which exist in a cavity array and to calculate the total energy delivered to these cavities by a passing relativistic electron bunch. The average energy loss predicted by Keil's theory was in reasonable agreement with our early experiments . Later, more refined experiments at SLAC shed significant additional light on the physical radiation lose process, showing how the position of the electron bunch with respect to the accelerating wave affects the results. This prompted G. Loew at SLAC to devise a semiempirical analysis of the problem for which a computer program was written by R. Early and B. Woo. This analysis not only yields the average loss for the entire electron bunch but can also give the energy loss as a function of time within the bunch and the resulting energy spectrum. The only additional element that was necessary to complete this theory was the function giving the response of the SLAC three-kilometer cavity array to a delta-function beam excitation. This function was supplied by P. Wilson and K. Bane at SLAC, who had obtained Keil's program in order to apply it to the design of storage ring cavities for the PEP project, and who simply performed a modal sum in the time domain of all the accelerator modes. G. Loew's theory, which now incorporates the Wilson-Bane function, gives very good agreement with our measured results. …

01 Sep 1976
TL;DR: In this article, a discussion of how the technology of linear induction accelerators, well known to be matched to high current and short pulse length, may offer significant advantages for this application is given.
Abstract: There is considerable recent interest in the use of high energy (..gamma.. = 1.1), heavy (A greater than or equal to 100) ions to irradiate deuterium--tritium pellets in a reactor vessel to constitute a power source at the level of 1 GW or more. Various accelerator configurations involving storage rings have been suggested. A discussion is given of how the technology of Linear Induction Accelerators--well known to be matched to high current and short pulse length--may offer significant advantages for this application.

01 Jan 1976
TL;DR: In this article, an analysis of the input parameters of an Alvarez type drift-tube accelerator is presented, and it is shown that an accelerator operating at a frequency of 50 MHz is capable of accepting deuteron currents of about 0.4 amperes and proton currents of 1.2 ampere, depending on the assumed values of beam emittance and on the ability to properly match this to the linac acceptance.
Abstract: Recent emphasis on alternative energy sources together with the need for intense neutron sources for testing of materials for CTR has resulted in renewed interest in high current (approximately 100 mA) c.w. proton and deuteron linear accelerators. In desinging an accelerator for such high currents, it is evident that beam losses in the machine must be minimized, which implies well matched beams, and that adequate acceptance under severe space charge conditions must be met. An investigation is presented of the input parameters to an Alvarez type drift-tube accelerator resulting from such factors. The analysis indicates that an accelerator operating at a frequency of 50 MHz is capable of accepting deuteron currents of about 0.4 amperes and proton currents of about 1.2 amperes. These values depend critically on the assumed values of beam emittance and on the ability to properly ''match'' this to the linac acceptance.

01 Jan 1976
TL;DR: The Fermilab accelerator as mentioned in this paper is comprised of four major systems: the high-energy beam extraction and switching system, the main accelerator (main ring), the booster, and the linear accelerator.
Abstract: The Fermilab accelerator is comprised of four major systems: the high-energy beam-extraction and switching system, the main accelerator (main ring), the booster, and the linear accelerator. The Fermilab accelerator produces accelerated beams for a vigorous international high-energy physics program. The basic design features and operation for high-energy physics have been described a number of times in the past. A report is given which, for the most part, discusses in detail only those features that are particularly significant in increasing the usefulness of the accelerator as a tool for high-energy physics.

Journal ArticleDOI
TL;DR: In this paper, the relationship between radiation output and monitor units was found to vary by as much as 10% and the central-axis depth dose remained constant within experimental error, and a mechanism for the change in calibration was suggested based upon field flatness measurements.
Abstract: Variations in the output with a fixed monitor unit setting as a function of magnetron power of a 4-MV linear accelerator has been studied. The relationship between radiation output and monitor units was found to vary by as much as 10%. The central-axis depth dose was found to remain constant within experimental error. Field flatness measurements indicated that for lower power outputs, the radiation field was less flat than for higher power outputs. A mechanism for the change in calibration is suggested based upon field flatness measurements.

Journal Article
TL;DR: The results of this study show not only that it is essential to take into account the recombination of ions when ionisation chambers are used to calibrate the irradiation beams of new accelerators for medical use, but also that the effectiveness of the collection of ions is dependent upon the electronic equipment associated with the chamber.
Abstract: The difference of potential of supply of ionisation chambers is often inadequate to collect all the ions formed under the effects of a pulsed ray The authors thus decided to determine the effectiveness of the collection of ions in one of the types of cylindrical ionisation chambers used most commonly at present in calibrating teleradiotherapy beams : Nuclear Enterprises chambers type 2505/3 A and 3 B They determined essentially the value of effectiveness of the collection of ions using lithium borate, a thermoluminescent dosimeter the response of which is independent of dose up to very high flow rates In the case of a pulsed ray emitted at constant frequency, it is easy to evaluate the dose delivered by impulsion and then compare the values obtained experimentally with those calculated using theoretical formulae such as Boag's formula By contrast, in the case of an accelerator equipped with an electromagnetic sweep system of the beam in order to ensure a homogeneous dose of electrons, instantaneous flow doses (dose/impulsion) are difficult to evaluate by virtue of the sweep and variables from one type of energy to another The authors thus sought an empirical method making it possible to evaluate the effectiveness of the collection of ions, knowing the energy of the incident electron beam and the dose flow indicated by the ionisation chamber receiving its usual supply tension The results of this study as a whole show not only that it is essential to take into account the recombination of ions when ionisation chambers are used to calibrate the irradiation beams of new accelerators for medical use, but also that the effectiveness of the collection of ions is dependent upon the electronic equipment associated with the chamber

Journal ArticleDOI
TL;DR: In the past few months, a dazzling array of new particles have been discovered: ψ (3.4 GeV), ψ(3.5 GeV/c2) from Stanford Linear Accelerator (SLAC) and ψ 2.8 GeV from DESY, the German laboratory.
Abstract: Over the past few months press releases have announced a dazzling array of new particles: ψ (3.4 GeV), ψ (4.15), and ψ (4.45) from Stanford Linear Accelerator (SLAC) and ψ (2.8) and ψ (3.5) from DESY, the German laboratory – with reports from SLAC that there are two particles with masses near to 3.5 GeV/c2. These discoveries followed on from one of the most exciting developments in physics which took place just over a year ago (November 1974) with the discovery of a new strongly interacting particle (hadron) by independent teams of physicists working at the Brookhaven National Laboratory (BNL) and at SLAC.

Patent
17 Nov 1976
TL;DR: In this paper, an electronic linear accelerator that provides electronic line having good spectrum by performing correct line capacity control while using trident tube with grit as electronic gun, varying pulse frequency of output electronic current and optionally varying this pulse emplitude and time
Abstract: PURPOSE:An electronic linear accelerator, that provides electronic line having good spectrum by performing correct line capacity control while using trident tube with grit as electronic gun, varying pulse frequency of output electronic current and optionally varying this pulse emplitude and time

01 Jan 1976
TL;DR: A description of operating experience on the 200 MeV Proton Injector Linace of the A.G.S. is given in this paper, emphasizing developments in field phase and amplitude control and beam diagnostics.
Abstract: A description is given of operating experience on the 200 MeV Proton Injector Linace of the A.G.S. emphasizing developments in field phase and amplitude control and beam diagnostics. Developments in auxilliary use of the machine are also described.

Journal ArticleDOI
TL;DR: UNILAC as discussed by the authors is a linear accelerator that is expected to be capable eventually of accelerating heavy nuclei such as uranium to 10 MeV/nucleon and lighter nuclei, such as argon to 14 MeV /n. The accelerator is the first to accelerate heavy ions over the full periodic table.
Abstract: What will probably be the most completely equipped laboratory in the world for heavy‐ion research is now operating 20 km from Frankfurt. The laboratory, GSI (Gesellschaft fur Schwerionenforschung), houses UNILAC, a linear accelerator that is expected to be capable eventually of accelerating heavy nuclei, such as uranium to 10 MeV/nucleon and lighter nuclei, such as argon to 14 MeV/nucleon. When it is operating at full energy, for heavy nuclei, it will have the highest energy available in the world, at least for the immediate future. The accelerator is the first to accelerate heavy ions over the full periodic table.

Journal Article
TL;DR: The dosimetric characteristics of the electron beams from the Sagittaire (C.G.R. MeV) linear accelerator are presented and the preponderant influence of the short side 1 of the rectangular field of the relative variation in dose output is demonstrated.
Abstract: The dosimetric characteristics of the electron beams from the Sagittaire (C.G.R. MeV) linear accelerator are presented. The variations in dose output with the distance from the source are indicated for the usual treatment distances. The measurements carried out demonstrating the deviations from the inverse square law for distances. The graphs for the variation in dose output in terms of the opening of the collimator are given for square and rectangular openings. The measurements demonstrate the preponderant influence of the short side 1 of the rectangular field of the relative variation in dose output. The variations in the graphs of the deep yield in terms of beam energy, distance from the source and field dimension were studied. For the different energies, the influence of the distance from the collimator and the dimension of the field on the dose at entry and on the depth of the maximum was shown. Measurements of the deep yields were carried out in the case of rectangular fields. In each case, the side of the equivalent square field corresponding to the same deep yield as a 1 X L rectangular field was determined; a comparison was carried out with the equivalent square field defined for colbat radiation.

Journal ArticleDOI
TL;DR: Three-generation accelerators with 270 deg.
Abstract: Third-generation accelerators with 270 deg. "achromatic" electron-beam bending should combine construction with improved stability. Two-year performance records are presented to show that flatness has remained within +/-1 per cent with the first production model of the Radiation Dynamics "Dynaray-4" accelerator installed in Cardiff.

ReportDOI
01 Sep 1976
TL;DR: The SuperHILAC linear accelerator as mentioned in this paper is an Alvarez linear accelerator designed to accelerate all ions to a maximum energy of 85 MeV/u, which is the state-of-the-art in the world.
Abstract: The SuperHILAC is an Alvarez linear accelerator designed to accelerate all ions to a maximum energy of 85 MeV/u It functions as an essential part of two research programs of national importance--first, as a supplier of beams for research at less than 10 MeV/u, secondly as an injector for the Bevalac facility, for nuclear physics and medical research at energies greater than 200 MeV/u This duplication of effort from a single accelerator is made possible by the utilization of a technique known as timeshare--two different ion beams are accelerated independently through the same linac structure Recent operation has been in the mass range 12 less than or equal to A less than or equal to 136 Usually, a heavy ion (A greater than 40) is delivered to the SuperHILAC experimental area for nuclear physics experiments while concurrently delivering a lighter ion (A less than or equal to 40) to the Bevatron for further acceleration (max 25 GeV/u) to be used in experiments exploring the physics of very high energy heavy ions, in investigations of radiation biology, and in preclinical tests as a tool for cancer treatment Recent operating experience is reviewed Also discussed are recent major improvements which have beenmore » made to the accelerator, and a proposed improvement which will increase reliability and beam intensity for the very heavy ions (A greater than or equal to 84) by adding a third injector of improved design« less